Re: mod_perl2 + fork + DBI = Chaos

Just to follow up on this before anyone spends any time caring about it, 
the seg faults could also be because one of the zombie apache2 processes 
I've spawned like a Gremlin is answering the request and well...

So, if I've done the fork properly and pretend I have apache PIDs 1..10 
running, and the child is 11 and it does it's thing and hits 
CORE::exit(0) should that process then die?  Or will I now see apache 
processes 1..11?

What should I be looking for after a clean fork?

Tosh



Tosh Cooey wrote:
> I wish I could do SQL before the fork, but I need to update tables with 
> results in the forks.
> 
> Just to make things stranger, after I make a fork and things don't 
> happen the way I expect them, subsequent calls to other programs running 
> under mod_perl are generating Segmentation Faults.  This could be due to 
> the fact that the server is running in Europe and the SQL server in 
> North America.  I would really love to hear that this can cause 
> segmentation faults because otherwise I have no idea where they are 
> coming from and in all my years using this same framework in mp1, mp2 or 
> just vanilla CGI I have never seen so many segfaults.
> 
> Bah...
> 
> Tosh
> 
> 
> [email protected] wrote:
>> Have you been through these threads already?
>> The first one seems quite like what you're doing.
>>
>> http://mail-archives.apache.org/mod_mbox/perl-modperl/200908.mbox/%[email protected]%3E 
>>
>> http://www.gossamer-threads.com/lists/modperl/modperl/100099
>>
>> Is the time for the SQL inquiry so bad that you can't
>> just do the inquiry before the fork-and-exec bit?
>>
>> Best of Luck,
>> cmac
>>
>>
>> On Jan 25, 2010, at 8:07 AM, Tosh Cooey wrote:
>>
>>> My application-from-hell is doing odd things probably related to the 
>>> above storms and culminating in a perfect storm.
>>>
>>> Can anyone point me to resources outlining the best way to use the 
>>> combination in the subject line?
>>>
>>> There seems to be many ways of accomplishing specifics but very 
>>> little generic methodologies which can be adapted.
>>>
>>> What I'm trying to do is in a nutshell:
>>>
>>> ##########
>>> my $object_with_DBH = new My::DataObject;
>>>
>>> ... do stuff...
>>>
>>> if ($pid = fork) {
>>>     ... parent things ...
>>> } elsif (defined $pid) {
>>>   ... close STDhandles ...
>>>
>>>   my $data = $object_with_DBH->SQL('do SQL stuff with old connection');
>>>
>>>   exec 'things from $data';
>>>
>>>   CORE::exit(0);
>>> }
>>> ##########
>>>
>>> I've tried Stas' code but that's for MP1, and with $DBI->clone(), and 
>>> playing with "setsid" from POSIX and on... There seems to be no love 
>>> between mod_perl2, fork, and DBI.
>>>
>>> On a side, but possibly related note, my browser is sending a POST 
>>> request which results in the FORK above and the parent then sends a 
>>> 302 redirect with some status variables.  This works fine, except 
>>> between the POST and the 302 GET is another POST to the same URI 
>>> which results in a 500 error, here's the log:
>>>
>>> "POST /tosh/mailfile.pl HTTP/1.1" 302 282
>>>
>>> "POST /tosh/mailfile.pl HTTP/1.1" 500 424
>>>
>>> "GET /tosh/index.pl?message=Notice%20sent HTTP/1.1" 200 4309
>>>
>>> The browser only seems to see the middle one, the 500.  I'm certain 
>>> this is related to my poor forking above but I have no idea why.  Are 
>>> there any tools for Firefox that will let me track every connection 
>>> it's making and why?
>>>
>>> Thanks again for any help with my Frankenstein monster...
>>>
>>> Tosh
>>>
>>> -- 
>>> McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/
>>
>>
> 

-- 
McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/